It is already known from the German published application No. 26 30 019 to directly connect two coaxially disposed rotary parts of a lock to one another by way of an electromagnetic coupling device given coincidence of the input key information with the prescribed lock information.
The one part is accessible from the exterior and is designed as a rotary element which is rotatable by way of a handle inserted into a square opening. It comprises a first plate serving the purpose of closing and directly influencing a bolt and an electromagnet serving the purpose of opening and slaving a second plate directly influencing the bolt only when the electromagnet is excited, both as parts of the coupling device. Both the first plate and the coupling magnet can be turned together. In the one rotational sense, the first plate strikes an edge of the bolt by way of a projection and moves the bolt into the locked position. As a result of its shape, the first plate has no influence on the bolt in the other rotational sense, the bolt thus being incapable of being retracted. On the basis of the edges of an opening in the second plate, the second plate strikes a cog applied to the bolt and entrains the bolt in both directions insofar as a torque is applied to the second plate. This, however, is the case only when the electromagnet is excited.
In order to open the lock, it is therefore necessary that the magnetic connection between the electromagnet and the second plate has been produced. This connection must consequently exert the entire torque required for moving the bolt into the open position. This requires a strong electromagnetic field and, therefore, high electrical energy, in addition to a large format of the magnet.
The known arrangement, moreover, is susceptible to disruption, this being the reason that measures have been undertaken to enable opening even given outage of the electrical devices. The known arrangement, moreover, is very bulky and complicated.
For the above reasons, the known arrangement is mainly suitable only for larger vaults and the like. Its use is not meaningful in dwellings and portable containers and must also be foregone because of expense.